In-Orbit vignetting calibration of the XMM-Newton telescopes

Marcus KirschMarcus Kirsch

Science Operations & Data Systems Division Research & Scientific Support Department

Amon Presentation: 23 April 2002

XMM-NewtonXMM-Newton

In-Orbit vignetting calibration of In-Orbit vignetting calibration of the XMM-Newton telescopesthe XMM-Newton telescopes

Marcus G. F. Kirsch, D.H. Lumb, A. Finoguenov, Marcus G. F. Kirsch, D.H. Lumb, A. Finoguenov, R. Saxton, B. Aschenbach, P. Gondoin, R. Saxton, B. Aschenbach, P. Gondoin,

I. StewartI. Stewart

Marcus KirschMarcus KirschScience Operations & Data Systems Division

Research & Scientific Support Department


EPICEPICXMM-Newton MirrorsXMM-Newton Mirrors 3 Wolter Telescopes, with 58 3 Wolter Telescopes, with 58

concentric mirror shells eachconcentric mirror shells each

focal length: 7.5 m focal length: 7.5 m

angular resolution: angular resolution: 6 arcseconds (FWHM )6 arcseconds (FWHM )

point-spread function: point-spread function: 15 arcsec (HEW)15 arcsec (HEW)




EPICEPICVIGNETTINGVIGNETTING VIGNETTINGVIGNETTING – the reduction in effective – the reduction in effective

area with off-axis anglearea with off-axis angle iimportant formportant for::

– cluster surface brightnesscluster surface brightness– counts:flux conversions in population counts:flux conversions in population

study study – background normalisationbackground normalisation

oon-ground the X-ray measurements in n-ground the X-ray measurements in Panter were in Panter were in divergingdiverging beam and/or beam and/or the grating stacks and stray light baffle the grating stacks and stray light baffle were installedwere installed

iin n pparallel UV beam no measurement of arallel UV beam no measurement of energy dependenceenergy dependence

nneed to confirm the alignments survived eed to confirm the alignments survived thermal relaxation of optical bench, thermal relaxation of optical bench, launch, and AIV campaignslaunch, and AIV campaigns

mmeasure energy dependence in orbit easure energy dependence in orbit

D. Lumb




EPICEPICtypical Vignetting resulttypical Vignetting result compare vignetting with compare vignetting with

data in telescope data in telescope calibration filescalibration files

unexpected variations unexpected variations (~10%) in rel. vignetting (~10%) in rel. vignetting with azimuth in PNwith azimuth in PN

attributed initially to attributed initially to problems in BG problems in BG correction and/or correction and/or exposure time correctionexposure time correction

but relative variations but relative variations are correlated with are correlated with camera orientation camera orientation

possible misalignment of possible misalignment of the telescope axisthe telescope axis compared with nominal compared with nominal referencereference

pn, 11 arcmin from nominal boresight




EPICEPICmodifying telescope axismodifying telescope axis oon –ground data had n –ground data had

been inconsistent to been inconsistent to ~30 arcsec typically ~30 arcsec typically

mmirror alignment cube irror alignment cube either blocked or either blocked or possibly moved during possibly moved during AIV ? AIV ?

ffor each telescope could or each telescope could minimise discrepancies minimise discrepancies in measured vignetting in measured vignetting by positing by positing a telescope axis shift of a telescope axis shift of up to up to 11 arcmin arcmin

try to find sensitive method to determine the shift




EPICEPICthe 4 methodsthe 4 methods

source at source at

different different

positionposition

diffuse diffuse

backgroundbackground

source source

elongationelongation

coma clustercoma cluster

11

22

33

44




EPICEPIC3C58 and G21.5-0.9 3C58 and G21.5-0.9

M. Kirsch

D. Lumb




EPICEPICvignettingvignetting: the shift: the shift

MOS2 G21.5-09(stars) & 3C58 (squares)

pn center at DETX=340 DETY=1300

D.H. Lumb




EPICEPICdiffuse backgrounddiffuse background

hhigh galactic latitude igh galactic latitude background data sets background data sets compiled for cluster compiled for cluster studiesstudies

rremoval of most sources, emoval of most sources, and co-addition of and co-addition of different fields leaves a different fields leaves a very uniform surface very uniform surface brightness which should brightness which should track the vignetting track the vignetting

mmodified by the particle odified by the particle background – has different background – has different vignetting function vignetting function (cosmic rays flat, soft (cosmic rays flat, soft protons scatter down protons scatter down mirror system)mirror system)

D.H. Lumb




EPICEPICsource elongationsource elongation

With increasing With increasing off-axis angles off-axis angles sources become sources become elongated (in elongated (in direction direction tangential to their tangential to their radius vector)radius vector)

Plot elongation vs. Plot elongation vs. angle to define angle to define centroid via centroid via mirror geometric mirror geometric propertiesproperties

R. Saxton




EPICEPICComa clusterComa cluster

aa repeat observation of repeat observation of the cluster centre was the cluster centre was made at new positmade at new positiion on angleangle

ccomparing surface omparing surface brightness in same sky brightness in same sky region reveals under- or region reveals under- or over-correction (dotted over-correction (dotted line)line)

aadjust the centroid of djust the centroid of vignetting function to vignetting function to minimise these minimise these differences (solid line)differences (solid line)

A. Finoguenov




EPICEPICposition of optical axisposition of optical axis

method MOS1 X MOS1 Y MOS2 X MOS2 Y PN X PN Y

G21.5 -09 60 +/-200

(-)230 +/-200

400 +/-200

(-)1350 +/-200

1250 +/-200

280 +/-200

Diffuse Background 0 +/-200

0 +/-200

300 +/-200

(-)1300 +/-200

1100 +/-200

340 +/-200

Source Elongation (-)320 +/-200

540 +/-200

(-)340 +/-200

(-)1700 +/-200

1140 +/-300

320 +/-300

Coma Cluster 110 +/-40

(-)200 +/-70

550 +/-60

(-)1255 +/-30

1243 +/-30

402 +/-30

3C58 + G21.5 - 0.9 200 +/-200

(-)50 +/-200

340 +/-200

(-)1300 +/-200

1300 +/-500

450 +/-500

detector co-ordinates (0.05 arcsec)




EPICEPICposition of optical axisposition of optical axis

method MOS1 X MOS1 Y MOS2 X MOS2 Y PN X PN Y

Coma Cluster 110 +/-40

(-)200 +/-70

550 +/-60

(-)1255 +/-30

1243 +/-30

402 +/-30

3C58 + G21.5 - 09 200 +/-200

(-)50 +/-200

340 +/-200

(-)1300 +/-200

1300 +/-500

450 +/-500

optics_X/Y (PIXCOORD) 305 291 325 243 23 183

optics_X/Y MISC_0019 300 300 300 300 39 188

difference in pixel -5 9 -25 57 16 5

difference in arcsec -5.5 9.9 -27.5 62.7 65.6 20.5

currently under testing in DT SAS




EPICEPICcalculate new BS anglescalculate new BS angles

the new optical axis position required the new optical axis position required a set of new Boresight CCFs which a set of new Boresight CCFs which hold for each instrument a triple of hold for each instrument a triple of three angles describing the three angles describing the misalignment of the respective misalignment of the respective instrument boresight with respect to instrument boresight with respect to the satellite coordinate frame the satellite coordinate frame

using the OMC2/3 field new BS using the OMC2/3 field new BS misalignment angles for all the three misalignment angles for all the three cameras have been calculatedcameras have been calculated

goal: astrometry should not goal: astrometry should not change!!!!!!!!!change!!!!!!!!!




EPICEPICastrometry: EPIC-2MASS astrometry: EPIC-2MASS

RA offset: -0.47 arcsecDEC offset: -0.55 arcsec






B. Altieri

old optical axis and BS:

new optical axis and BS




EPICEPIC3C58 results for MOSs3C58 results for MOSs

3C58 Vignetting check

0.85

0.9

0.95

1

1.05

1.1

1.15

16 18 20 22 24 26

obse rvationco

nst

in m

odel mos2_old

mos2_new

mos1_old

mos1_new

3C58 Vignetting check

0.9

0.95

1

1.05

1.1

1.15

4 4.5 5 5.5 6 6.5

off axis angle in arcm inn

orm

fac

tor mos1 old

mos1_new

mos2_old

mos2_new

Model: constant[1]*wabs[2]( powerlaw[3] )

?

• flux variation off axis reduced from ± 10 %

down to ± 1-2 % for both MOSs

• pn to be checked with Coma/G21.5-09

observations

M. Kirsch

M. Kirsch




EPICEPICmissing/finding the gapmissing/finding the gap

in order to recover in order to recover properly the flux sources properly the flux sources should not fall onto CCD should not fall onto CCD gapsgaps

also the condition of the also the condition of the right off axis angle must right off axis angle must be taken into accountbe taken into account

8 observations have been 8 observations have been optimised for thatoptimised for that

....one not enough ....one not enough




EPICEPIC

absolute timing accuracy newsabsolute timing accuracy news

in in Proc. SPIE 5165

Timing accuracy and capabilities Timing accuracy and capabilities of XMM-Newtonof XMM-Newton M. G. F. KirschM. G. F. Kirsch1)1), W. Becker, W. Becker5)5), S. Benlloch-Garcia, S. Benlloch-Garcia4)4), F. A. Jansen, F. A. Jansen2) 2) , ,

E. KendziorraE. Kendziorra4)4), M. Kuster, M. Kuster5)5), U. Lammers, U. Lammers2)2), A. M. T. Pollock, A. M. T. Pollock1)1), , F. PossanziniF. Possanzini3)3), E. Serpell , E. Serpell 3)3), A.Talavera, A.Talavera1)1)




EPICEPIC

EPIC-pn

quadrantclocksquadrantclocksquadrantclocksquadrantclocks

UTCUTC

OBTOBT

100 100 ss

50 50 ss

30 30 ss

orbit predictionorbit prediction20 20 s s XMCSXMCS

+- 10 +- 10 ss

th. absolute accuracyth. absolute accuracy

theoretical upper limit for absolute theoretical upper limit for absolute time uncertainties is <100 time uncertainties is <100 s s

the limited number of analyses the limited number of analyses conducted so far indicated in the past conducted so far indicated in the past that the actual error is larger (~1ms)that the actual error is larger (~1ms)




EPICEPICa. accuracy: a. accuracy: the bugthe bug

wrongly corrected CDMU delay (626.17 wrongly corrected CDMU delay (626.17 s)s)

delay was erroneously subtracted instead of addeddelay was erroneously subtracted instead of added

--> shift of 1252.34 --> shift of 1252.34 s.s.

correction will be implemented in new time correction will be implemented in new time correlationcorrelation

work around will be issued on XMM-Newton-SOC work around will be issued on XMM-Newton-SOC pages pages

UTC(OBT) = ERT UTC(OBT) = ERT ++ (CDMU) - (CDMU) - (Flight) - (Flight) - (G/S)(G/S)

(for details see Kirsch et al. Proc. SPIE 5165)




EPICEPICabsolute timing with the Crababsolute timing with the Crab

f_rad f_xmm MXP 1-MXP 1-MXPOrbit OBS ID [Hz] [Hz] [phase] [phase] [ ms ]

56 0122330801 29.84375911 29.8437591143 0.98174 0.01830 0.60350234 0135730701 29.83195269 29.8319526890 0.98723 0.01270 0.44256411 0153750201 29.82015493 29.8201549266 0.98845 0.01150 0.40233411 0153750301 29.82015493 29.8201549266 0.98910 0.01090 0.36210411 0153750401 29.82015493 29.8201549266 0.98996 0.01000 0.32187411 0153750501 29.82015493 29.8201549266 0.98989 0.01010 0.32187

absolute timing accuracy: ~300-600 absolute timing accuracy: ~300-600 ss

in agreement with Crab observations performed by RXTE and in agreement with Crab observations performed by RXTE and Chandra Chandra

opportunity to opportunity to contemporaneously observe the Crab with Chandra contemporaneously observe the Crab with Chandra and in the opticaland in the optical using an MPE developed fast photometer to get a using an MPE developed fast photometer to get a radio-ephemeris independent phase solution between the optical and radio-ephemeris independent phase solution between the optical and X-ray pulses in REV: X-ray pulses in REV: NRCO scheduled Rev 696NRCO scheduled Rev 696 2003-09-28T04:17:05 2003-09-28T04:17:05





EPICEPICEPIC data anomaliesEPIC data anomalies

pn-AUX data anomalies :– frequency of occurrence is varying – unrelated to camera mode, observing

time and/or duration– random negative or positive jumps in random negative or positive jumps in

FTCOARSE not found occasionally by FTCOARSE not found occasionally by SASSAS

pulse peak broadening, phase shift spurious pulse components

SAS 6.0 (winter 2003 ? ): SAS 6.0 (winter 2003 ? ): refined detection/correction algorithm --> all problems will reliably found and corrected

W. Becker

M. Kirsch


In-Orbit vignetting calibration of the XMM-Newton telescopes

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